Question: 2 crayons cost $2.86. Which equation would help determine the cost of 14 crayons?
Answer: There are several equations that could help determine the cost, each with a slightly different approach. We know the cost of 2 crayons. We want to know the cost of 14 crayons. We can write the numbers of crayons as a proportion: $\dfrac{2}{14}$ We know 2 crayons costs $2.86. We can let $x$ represent the unknown cost of 14 crayons. The proportion of these costs can be expressed as: $\dfrac{\$2.86}{x}$ The cost changes along with the number of crayons purchased, and so the two proportions are equivalent. $\dfrac{2}{14} = \dfrac{\$2.86}{x}$